Lecture #16
AcidBase Titrations II and III
The titration of diprotic and polyprotic systems applies the same principles used for
monoprotic systems.
Example: A diprotic weak base (0.100 M, 10.0 mL) with pKb1 = 4.00 and pKb2 = 9.00
titrated with a strong
Lecture #10
Monoprotic Acids & Bases I and II
Nanoscale pH probe
The probe consists of
hundreds of packed
ZnO nanorods, each
80 to 100 nm in
diameter and 700 to
900 nm in length.
The probe tip is about
1.4 microns in diameter
and can penetrate the
membra
Problem 911: A 0.045 M solution of benzoic acid has a pH of 2.78. Calculate
the pKa for this acid.
Assume activity coefficients = 1
pH = log[H+]
[H+] = 102.78
[H+] = 1.66 x 103 M
Lecture 10_Solved Problems
Ka = x2 / F  x
= (1.66 x 103)2 / (0.045  1
Lecture #14
Polyprotic Acids & Bases III and IV
Which is the Principal Species?
HA + OH H2O + AHA
H+ + A 
pH
Ka = [H+] [A] / [HA]
0
CHM 326, lecture 14, 2/22/16
Ve/2
Ve
Volume of base
1
How much of each species is present at a given value of pH?
Consi
Lecture #15
Acid Base Titrations I
CHM 326, lecture 15, 2/23/16
1
Titration of a Strong Base with a Strong Acid
Example: NaOH + HCl
When considering [H+] and [OH] only consider the following reaction:
OH + H+ H2O
K = 1/Kw = 1014
Question: If 50.00 mL of
Lecture #13
Polyprotic Acids & Bases II
(HG)
Ka2
Ka1
(G)
(H2G+)
(G)
CHM 326, lecture 13, 2/19/16
1
Generalized Calculations for Diprotic Acids
A. Calculate the pH and composition of solutions ([HA], [H2A], and [A2]) produced
when starting with the acid
Lecture #11
Monoprotic Acids & Bases II and III
How many kinds of buffers are there? Lots!
CHM 326, lecture 11, 2/15/16
1
Buffers
The importance of buffers (weak acid + its conjugate base) cant be overestimated.
Key Characteristics of a Buffered Solutio
Lecture #13
Polyprotic Acids & Bases II
(HG)
Ka2
Ka1
(G)
(H2G+)
(G)
CHM 326, lecture 13, 2/19/16
1
Generalized Calculations for Diprotic Acids
A. Calculate the pH and composition of solutions ([HA], [H2A], and [A2]) produced
when starting with the acid
Lab #2  Calibration
Part 1 Measurements: You will measure out 25 mL of DI water at 5 stations (15)
around the lab. At each station a different piece of volume measurement equipment
will be used.
Purpose of Measurements: To evaluate the provided pieces o
CHM 326  Lab 2: Calibration
In this lab exercise you will practice some fundamental laboratory skills involving the use
of laboratory glassware, calibration, and the determination accuracy and precision. Read
the section 29 (p. 3839) in Harris on the c
Procedures
Use an analytical balance to weigh out 0.5 g of THAM (Tris(hydroxymethyl)aminomethane).
Dissolve the THAM in an Erlenmeyer flask containing 50 ml of distilled water and swirl to
dissolve. Add 24 drops of Bromocresol Green indicator to the THAM
CHM 326, Lecture #8
Activity and Equilibrium II
Q: How do we determine the concentrations of species in complex equilibria?
A: Use the Systematic Approach to Equilibrium (p.169 182)
Process: Write one equation for every unknown concentration in a given e
CHM 326, Lecture #5
Chemical Equilibrium II (Chap. 6)
CHM 326, lecture 5, 1/29/16
1
Complex Formation (p. 126129)_
We said last time that ions can be separated based on differing values of Ksp
Example: A solution contains 0.001 M in both Cu+ and Ag+. If
CHM 326, Lecture #3
Statistics (Chap. 4)
Measurement Error is Best Quantified Using Statistics
Quotes on the usefulness of statistics:
There are three types of lies  lies, damn lies, and statistics.
Statistics can be made to prove anything  even the tru
CHM 326, Lab #3,
Preparation of the Oral Report
Oral reports will be presented during the regularly scheduled lab during the week of 2/31.
Oral reports will be 1015 minute PowerPoint presentations given by each team. All
members of each team will prese
Lab #3  Determination of Ka
Purpose of Lab: Perform a precise determination of Ka for a weak acid using two
methods of analysis, with and without considering activity in the determination.
Experimental: Work to be done in teams of two. Review detailed pr
Problem #1: Calculate the number of nanometers (nm) in 10 Angstroms ().
1 = 108 cm
1 nm = 109 m
Convert nm to cm:
1 nm = 109 m (102 cm/m)
1 nm = 107 cm
(1)
Multiply both sides of (1) by 101:
(101) 1 nm = 107 cm (101)
0.1 nm = 108 cm
0.1 nm = 1
1
Problem # 1: Calculate the absolute uncertainty in the determination of the perimeter
for the gold nanotriangle below.
5.2
2+
3.91 + 0.01 nm
a
c
0.0
3n
m
What is the perimeter of a triangle?
Perimeter of a triangle = a + b + c
= 3.91 + 4.37 + 5.22
= 13.5
Problem #1 (638, p. 143):
The equilibrium constant for the reaction H2O
What is the value of K for the reaction 4H2O
Write the expression for K in the case of 4H2O
(
4H+ + 4OH
[H+] [OH] 4
= ([H+] [OH])4 = Kw4 = (1.0 x 1014)4 = 1.0 x 1056
[H2O ]
(
[H
Problem 911: A 0.045 M solution of benzoic acid has a pH of 2.78. Calculate
the pKa for this acid.
Assume activity coefficients = 1
pH = log[H+]
[H+] = 102.78
[H+] = 1.66 x 103 M
Lecture 10_Solved Problems
Ka = x2 / F  x
= (1.66 x 103)2 / (0.045  1
Lecture #19
Electrochemistry I
CHM 326, lecture 19, 3/9/16
1
Electrochemistry provides a host of techniques for quantitative analysis
Basics of Electrochemistry:
1.Recognize the difference between oxidation and reduction and at which
electrodes they occur
Problem 1013 (p. 231) How many mL of 0.202 M NaOH should be added to 25.0 mL
of 0.0233 M salicylic acid (2hydroxybenzoic acid) to adjust the pH to 3.50?
H2SI + OHH2Sl
HSI + H2O
H+ + HSl
pK1 = 2.972
HSlH+ + SlpK2 = 13.74
salicylic acid H2Sl
pH of inter
Problem 1111: Use activity coefficients to calculate the pH after 10.0 mL of
0.100 M trimethylammonium bromide was titrated with 4.0 mL
0.100 M NaOH.
(CH3)3NH+ + OH
(CH3)3NH2
+
H 2O
What is the equivalence point?
MaVa = MbVb
Vb = (0.100)(0.0100) / (0.10
942: Calculate the pH of a solution prepared by mixing 0.0800 mol of chloroacetic
acid plus 0.0400 mol of sodium chloroacetate in 1.00 L of water.
c) Using first your head, then the HH equation, find the pH of a solution prepared by
dissolving all of th
Problem 1131: How many grams of dipotassium oxalate (FM = 166.22) should be
added to 20.0 mL of 0.800 M HClO4 to give a pH of 4.40 when the
solution is diluted to 500 mL?

O2CCO2 + H+ HO2CCO2
HO2CCO2 + H+ HO2CCO2H
HO2CCO2H
HO2CCO2
H+ + HO2CCO2
pK1
Problem 1025 (p. 231)
The base B has a pKb = 5.00
B + H2O
BH+
BH+ + OH
Kb = [BH+][OH]/[B]
H
Ka = [H+][B]/[BH+]
+ B
(a) What is the value of pKa? 9.00
(b) At what pH is [BH+] = [B]? 9.00
(c) Which is the principal species
at pH = 7.00? BH+
[BH+]
[B]
p